An actuator is a mechanical component of a switch assembly that interfaces with the metal dome to depress it to switch closure. Actuators often enhance the feel of a switch by focusing force to the middle of the metal dome. A proper actuator is essential to receive the best tactile feedback from your assembly.
An actuator that is too large can damage the dome, reduce life, or cause it to go bistable—meaning the dome does not return to its intended resting state after activation. For the best results, use a flat bottom plunger with no more than 25% of the dome’s diameter. Anything larger can cause undue stress on the metal domes, severely diminishing the feel, resulting in switch failures. Always place actuators at the center of the dome.
|Types of Actuator
|Actuator geometry molded into the silicone overlay. Proper geometry will provide a crisp feel with slightly deadened acoustics.
|Proper geometry will provide a crisp feel with no hampering of the acoustics.
|Proper geometry will provide a crisp feel with slightly higher acoustics.
|Graphic Overlay (with finger press)
|They are used in extreme low-profile assemblies. With no actuator built-in, having to finger press may reduce the feel of the switch.
|Used for backlit domes when the LED’s cannot be reverse mounted. The actuator has a relief cut to allow for the LED to project through when the dome is fully compressed.
Metal Domes with Built-In Actuators
Some metal dome designs feature a reverse dimple on the top of the dome that serves as a built-in actuator. The integrated actuator helps concentrate the applied force. Also, metal domes with built-in actuators show more consistent force patterns and tactile response when used with larger diameter actuators. They also help correct off-center actuations. When an actuator is not aligned correctly, a dome with a built-in actuator reduces the adverse effects caused by misalignment. This is particularly beneficial when working with smaller metal domes, where perfect center alignment can be challenging to achieve.
Integrated Actuator Versus Standard Dome
The chart below shows the decline of the tactile ratio of a conventional metal dome as compared to a dome with a built-in actuator when actuated in increasingly off-center increments.
Testing a built-in actuator dome with your unique switch assembly is the best way to determine if this dome switch solution is right for your product. Request free samples of integrated actuator domes, also known as the TC-Series, by contacting us today.